This Is How You Lose The Time War is a lot of fun.
I'm only a short way through it, but it avoids the usual time travel tropes in favour of a back-and-forth rivalry between two agents of opposing time-travel-capable factions, which starts off as taunting/professional-recognition kinda vibe, and plunges into nemesis-rivalry-flirting with wanton abandon via meticulously planned pranking-come-sabotage of each other's missions.